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This paper presents the design and implementation of a three-phase buck type unity power factor rectifier used for distribution systems. The AC-DC converter topology considered in this paper is named as SWISS rectifier, consists of front-end three-phase diode bridge rectifier with active current injection circuit and back-end DC-DC buck converter. The characteristics of the AC-DC converter topology, including the principle of operation, modulation schemes, conduction state analysis, and control strategy are discussed in detail. Further, the analytical expression for the loss calculation is performed. Extensive simulation is carried out for the converter system, and the practicability of the converter system is verified by conducting a test on the constructed hardware prototype.

This paper presents a technique for recognizing the single stage and multiple PQ (Power Quality) events using an algorithm based on ST (Stockwell's-Transform) and ANN (Artificial Neural Network) based classifier and a rule based decision tree. The ST which combines elements of WT (Wavelet Transform) and STFT (Short-Time Fourier Transform) is used for the analysis of various single stage and multiple power quality events. Single stage PQ events such as sag, swell, interruption, harmonics, transients, notch, spike, flicker and multiple power quality events which include the harmonic disturbances with sag, swell, flicker and interruption are analyzed using the proposed algorithm. A data base of these events is generated in MATLAB as per IEEE-1159 standard. Significant features of various PQ events are extracted using the S-transform and are used as an input to this hybrid classifier. The results are presented for the effective recognition of the PQ events with the proposed algorithm.

In this paper, a composite control strategy for improved off-grid configuration based on photovoltaic (PV array), a wind turbine (WT), and a diesel engine (DE) generator to achieve high performance while supplying nonlinear loads is investigated. To operate the WT efficiently under variable speed conditions and to obtain accurate and fast convergence to the maximum global operating point without a speed sensor, an iterative interpolation method is integrated with the perturbation and observation (P&O) technique. To ensure the balance of power in the system and to achieve the maximum power from the PV array without using any maximum power point tracking (MPPT) method, and ensuring stable operation during the disturbance, a double-loop control strategy for a two-switches buck-boost converter is developed. Furthermore, to protect the synchronous generator of the diesel generator (DG) from the 5th and 7th order-harmonics created by the connected nonlinear loads and to solve the issue of the filter resonance, the interfacing three-phase inverter is controlled using an improved synchronous-reference frame algorithm (SRF) with virtual impedance active damping. The presented work demonstrates effective and efficient control along with improved performance and cost-effective option as compared to the similar works reported in the literature. The performance of the presented off-grid configuration and its developed composite control strategy are tested using MATLAB/Simulink and validated through small-scale hardware prototyping.

ABSTRACT The paper deals with the new approach for the design of three-phase reluctance motors. Three different criteria are considered based on different practical constraints while seeking the optimum design for its improved steady state performance. A solid steel rotor structure is chosen for the ease of manufacture and to maintain its robustness as cage induction motor. The stator design is assumed as normal induction motor and only rotor parameters are considered as variables to achieve the goal. The developed technique results the improved design in small effort and has been employed to three different rating motors.

This paper deals with the performance analysis of a two-level, 24-pulse voltage source converters (VSCs) for high voltage DC (HVDC) system for power quality improvement. A two level VSC is used to realize a 24-pulse converter with minimum switching loss by operating it at fundamental frequency switching (FFS). The performance of this converter is studied on various issues such as steady state operation, dynamic behavior, reactive power compensation, power factor correction, and harmonics distortion. Simulation results are presented for a two level 24-pulse converter to demonstrate its capability.

This paper presents a new control scheme for a voltage source active filter (AF) which compensates, simultaneously, the harmonics and reactive power of nonlinear loads. The reference compensating currents are estimated from computed reference supply currents and sensed load currents. Reference supply currents are estimated using the active power of the load and the AF. A hysteresis or carrier-based PWM current control scheme is employed to generate the gating signals to the devices of the AF. A three-phase diode rectifier with capacitive resistive loading is used as a nonlinear load. Experimental results of a DSP-based prototype are presented to confirm the effectiveness of the new control scheme.

This paper presents an in-depth comparison of two possible schemes to supply 1-phase loads from self excited induction generators (SEIGs). These schemes employ 2-phase (asymmetrical) and 3-phase (symmetrical) stator windings with a squirrel cage (brushless) rotor and appropriate capacitor topologies. Among the different topologies proposed in literature for good voltage regulation and maximum power output, this paper investigates both the schemes to arrive at best configuration and provides a critical comparison to guide prospective users. General analytical models for both systems are presented and simulation methods explained. Comparison is made between both machines built in same frame based on computed and measured results. For constant speed prime movers such as bio-energy fed engines and hydro-turbines, it is possible to evolve a simple and user-friendly system based on this study that shows great promise for remote area electrification.

This paper deals with the design, analysis and simulation of neural network based DSTATCOM controller. Conventional controllers being fixed structure provide optimum performance only over a limited range of operating conditions for which they are designed. Alternate controllers based on fuzzy logic and neural networks are more robust and can be designed to operate well under a wide range of operating conditions. This paper highlights the performance of artificial neural network (ANN) based DSTATCOM controller with respect to PI controllers.

Abstract In this paper Scott-transformer supported three-phase four-wire unified power quality conditioner (3P-4W UPQC) is proposed and compared with different magnetics supported 3P-4W UPQC. Moreover, these magnetic supported 3P-4W UPQCs are also compared with the most commonly used four-leg VSI based 3P-4W UPQC in terms of % total harmonics distortions (THD) of source current and load voltage. A comparative analysis of required hardware and KAV rating of different magnetics is also given to choose the best option. A control strategy based on synchronous reference frame (SRF) with in-direct approach is used for the control of 3P-4W UPQCs. In this in-direct approach, the current/voltage control is applied over the fundamental supply currents/voltages instead of fast changing APFs currents/voltages, thereby reducing the effect of computational delay and required numbers of current sensors. The performances of the proposed topologies of UPQC are analyzed through simulations using MATLAB software with its Simulink and Power System Block set toolboxes .

This paper presents a multi-leg variable frequency converter based electric vehicle (EV) charger with improved adaptive current modulation strategy for fast charging operation from a single-phase distribution grid. The multi-leg bridgeless converter provides a higher utilization of input energy with a reduction in electromagnetic interference (EMI). The proposed configuration is more robust towards frequent parameter variation as the high-frequency converter leg reduces the requirement of large passive components. An adaptive sliding mode control (ASMC) has been introduced for faster dynamical control during grid-to-vehicle (G2V) and vehicle-to-grid (V2G) with diverged distribution grid conditions. The ASMC provides a better dynamical response as the tracking error is confined within the pre-defined sliding surface during an abrupt change in adaptive gain variation. The proposed control action virtually eliminates the proportional-integral (PI) controller to address more nonlinearities during the EV charging operation. A MATLAB & SIMULINK model is developed to study the various dynamical response of the converter and proposed control action. A hardware laboratory prototype is also designed for a 3.3 kW EV charger to validate the desired character with the improvement of the source-end power factor during active power exchange in the G2V mode of operation.